【leetcode】Merge Intervals

Merge Intervals

Given a collection of intervals, merge all overlapping intervals.

For example,
Given [1,3],[2,6],[8,10],[15,18],
return [1,6],[8,10],[15,18].

 

 

先排序，然后循环合并

 

 1 /**

 2  * Definition for an interval.

 3  * struct Interval {

 4  *     int start;

 5  *     int end;

 6  *     Interval() : start(0), end(0) {}

 7  *     Interval(int s, int e) : start(s), end(e) {}

 8  * };

 9  */

10 class Solution {

11 public:

12     vector<Interval> merge(vector<Interval> &intervals) {

13         vector<Interval> result;

14         if(intervals.empty()) return result;

15        

16         sort(intervals.begin(),intervals.end(),cmp);

17        

18         int start=intervals[0].start;

19         int end=intervals[0].end;

20        

21         for(int i=1;i<intervals.size();i++)

22         {

23             if(intervals[i].start<=end)

24             {

25                 //注意[1,4],[2,3]的情况

26                 end=end<intervals[i].end?intervals[i].end:end;

27             }

28             else

29             {

30                 result.push_back(Interval(start,end));

31                 start=intervals[i].start;

32                 end=intervals[i].end;

33             }

34         }

35  

36         result.push_back(Interval(start,end));

37         return result;

38     }

39    

40     static int cmp(const Interval &a,const Interval &b)

41     {

42         if(a.start<b.start) return 1;

43         else if(a.start>b.start) return 0;

44         else return a.end<b.end;

45     }

46 };